Dry cleaning

ABSTRACT

A method of dry cleaning of goods in which the majority of the solvent present in the goods at the conclusion of the actual cleaning is recovered by circulating air, by means of a fan, through the goods in a dry cleaning drum and through a watercooled condenser and a heating element, and then a small remaining amount of solvent is removed from the goods by a deodorizing operation, in which air is passed in a closed circuit through the goods in the dry cleaning drum and over a refrigerated surface on which the solvent is condensed.

United States Patent [1 1 Moore Apr. 30, 1974 DRY CLEANING [75] Inventor: William F. Moore, Guildford,

21 App]. No.: 233,892

[30] Foreign Application Priority'Data- Mar. 25, 1971 Great Britain 7818/71 May 5, 1971 Great Britain... 13315/71 [52] US. Cl. 8/142, 68/18 C [51] Int. Cl D06l l/02, D061 1/10, D06f 43/08 [58] Field of Search 68/18 R, 18 C; 34/77; 8/142 [56] References Cited UNITED STATES PATENTS 3,426,446 2/1969 Lotzsch 68/18 C X 5/1972 Victor 8/142 6/1973 Hyams 68/18 C Primary Examinerl-larvey C. Hornsby Assistant ExaminerPhilip R. Coe Attorney, Agent, or Firm-Larson, Taylor & Hinds [s7] TRACT A method of dry cleaning of goods in which the majority of the solvent present in the goods at the conclusion of the actual cleaning is recovered by circulating air, by means of a fan, through the goods in a dry cleaning drum and through a water-cooled condenser and a heating element, and then a small remaining amount of solvent is removed from the goods by a deodorizing operation, in which air is passed in a closed circuit through the goods in the dry cleaning drum and over a refrigerated surface on which the solvent is condensed.

6 Claims, 4 Drawing Figures PATENTEDAPR 30 I974 3 807L948 SHEET 1 OF 3 24b T: j:- 3,226

PATENTEDAPR 30 I974 SHEET 3 [IF 3 I 1 DRY CLEANING In the process of dry cleaning of clothes or other goods using perchlorethylene as a solvent, the majority of the perchlorethylene present in the goods at the conclusion of the actual cleaning is recovered by circulating air, by means of a fan, through the goods in a dry cleaning drum and through a water-cooIed-condenser and a heating element. Following this-recovery, there is still a small amount of perchlorethylenein the goods which would give the goods an odour, and to deal with this there is a final stage known as deodorizing.

Hitherto the most usual procedure for deodorizing has been to slightly open the door of the dry cleaning drum or to automatically open an air entry valve, to operate the same fan as is used for recovery, and to open a connection to a chimney. This causes a flow of fresh air into the drum which displaces the solvent-laden air present in the drum and itself flows through the goods. This hasthe disadvantage that there is some loss of perchlorethylene through the chimney to the atmosphere. Furthermore, the discharge of perchlorethylene to the atmosphere may be regarded as objectionable.

A modified procedure is to pass the air to the chimney through a carbon recovery plant inwhich the perchlorethylene is adsorbed. From time to time the perchlorethylene is expelled from the carbon recovery plant with the aid of steam.

Similar procedures can be used with other solvents, for example with trichlorethylene.

The present invention concerns an alternative procedure for deodorizing goods as a final stage in a dry cleaning process after recovery of themaj'ority of solvent by means of a water-cooled condenser.

This procedure may be used not only with perchlorethylene or trichloroethylene as solvent, but also with other solvents of high boiling points, and in particular, with 1,l,l trichloroethane.

In methods of dry cleaning of goods in accordance with this invention, the majority of the solvent present in the goods at the conclusion of the actual cleaning is recovered by circulating air, by means of a fan, through the goods in a dry cleaning drum and through a watercooled condenser and a heating element, and then a small remaining amount of solvent is removed from the goods by a deodorizing operation in which air is passed in a closed circuit through the goods in the dry cleaning drum and over a refrigerated surface on which the solvent is condensed.

By this means, there is no discharge to atmosphere and no chimney is required. The complication of a carbon recovery plant is avoided. The amount of odour in the goods can be reduced to the same low level as is obtained by existing procedures.

Moreover, when the door is opened at the conclusion of the deodorizing stage, there is no significant odour in the body of air in the drum which then becomes in communication with the atmosphere.

The present invention involves the use of both a water-cooled condenser and a refrigerated condenser. It is distinct from procedures, used with fluorinated hydrocarbons having a low boiling point, in which the entire recovery process is carried out by a refrigerated condenser. Such a use of a refrigerated condenser for the recovery process would be unnecessarily expensive in dry cleaning using solvents with higher boiling points.

Various examples of apparatus suitable for carrying out methods according to the invention will now be de scribed, with reference to the accompanying drawings, in which:

FIG. 1 is a circuit diagram;

- FIG. 1A shows a slight modification of FIG. 1;

FIG. 2 is a second circuit diagram; and

FIG. 3 is a diagramof a particular form of refrigerated surface.

The apparatus shown in FIG. 1 incluees a customary dry cleaning drum 2. The circuit for recovery of the majority of solvent present in the clothes at the conclusion of cleaning, after liquid has been drained into a tank 4, is constituted by ducting running from an outlet 6 from the drum to an inlet 8, and containing a dust filter 10, a fan 12, a condenser 14, and a heater 16. The condenser 14 is supplied with cooling water by means not shown.

For the purpose of deodorizing, there is additional ducting in parallel with the ducting containing the heater 16. This additional ducting leads through a second fan 18 and a chamber 20. In the chamber is a refrigerated coil 22 connected-to a refrigerating unit 24.

There are two dampers A and B which can be opened alternatively, to direct flow through the heater 16 or through the chamber 20. v

The term chamber is used for convenience, but in fact the enclosure for the coil 22 may simply be constituted by a portion of ducting of fairly large cross section. I

The refrigeration unit 24 is operated so as to maintain the surface of the coil 22 at a temperature of about 20C during deodorizing. Solvent condenses on this coil, but does not solidify.

Water evaporated from the goods during recovery is mostly condensed on the water-cooled condenser 14. Residual water vapour may form frost on the coil 22, but this will rapidly disperse at the conclusion of the deodorizing stage. A period of the order of 20 minutes elapses between the deodorizing stage of one cycle of operation and the same stage of the next cycle. During this interval the refrigeration unit 24 can be turned off. If necessary, defrosting of the coil can be augmented by passing warm air through the chamber 20 containing the coil.

The solvent condensed on the coil is collected and passed, by means not shown, through a water separator, to the liquid solvent circuit of the apparatus.

It is not necessary for the air which passes the coil 22 to be warmed before returning to the drum, but it is advantageous to continue to operate the water-cooled condenser 14 during the deodorizing stage.

FIG. 1A shows a modification of FIG. 1 in which the arrangement is more compact. The chamber 20 is immediately alongside the heater l6, and the second fan 18 is omitted. In place of two separate dampers, there is a single damper C which can be swung through FIG. 2 shows an arrangement which is simpler in construction, but otherwise less satisfactory. In this arrangement, the refrigerated coil 22a lies in a single ducting circuit, between the water-cooled condenser 14a and the heater 16a. A disadvantage of this arrangement is that, at the start of a recovery operation, the coil'22a is cold, and acts as a heat sink, even though the refrigeration unit 24a has been turned off. Hence the air flow past the coil is chilled, and part of the action of the heater 16a is spent in counteracting this chilling.

In the arrangements described so far, the refrigeration unit is operated only during the deodorizing operation. FIG. 3 shows a modification to FIG. 1 which enables a smaller refrigeration unit to operate continuously. In this modification, a refrigerated coil directly exposed to the air containing solvent vapour is replaced by a coil 22b, which lies within a vessel 26 which is filled with a liquid of high specific heat (e.g. glycol), and which has external fins 28. The vessel filled with glycol acts as a body of substantial thermal capacity, from which heat is removed continuously by the action of the refrigeration unit 24b, and which in turn can remove heat relatively rapidly from solvent in the air during the deodorizing operation only. A device, not shown, can be provided to detect any occasional accumulation of ice on the fins, and to thereupon initiate a defrosting action.

We have found that the best sequence of operation of the apparatus shown in FIG. 1 is to carry out recovery for about 9 minutes and then deodorizing for about minutes. This involves a shorter recovery time and a longer deodorizing time than in the usual procedure, but the total time is about the same.

The method according to the present invention is particularly suitable and advantageous for use in processes in which the solvent is 1,1,1 trichloroethane. One significant reason is that, at normal atmosphere temperature, trichloroethane has a high vapour pressure and is therefore especially unsuitable for handling by a carbon recovery plant.

For some years it has been known that l,l,l trichloroethane (CH CCl has a solvent action such as is required for dry cleaning. However, this trichloroethane was found to be unstable when subjected to distillation, and therefore was not used for dry cleaning.

Recently, compositions have become available on the market which include trichloroethane as a principal ingredient, together with a satisfactory stabiliser. Ac-

cordingly, trichlorethane can now be used as a dry cleaning solvent. It is available in the United Kingdom from Imperial Chemical Industries, Ltd. under the Trade Mark GENKLENE and on the continent of Europe from Solvay. The boiling point of the composition GENKLENE is given as falling in the range to C.

I claim:

1. A method of dry cleaning of goods in which the majority of the solvent present in the goods at the conclusion of the actual cleaning is recovered by circulating air, by means of a fan, through the goods in a dry cleaning drum and through a water-cooled condenser and a heating element, and then a small remaining amount of solvent is removed from the goods by a deodorizing operation, in' which air is passed in a closed circuit through the goods in the dry cleaning drum and over a refrigerated surface on which the solvent is condensed.

2. A method according to claim 1, in which during deodorizing the air is passed through the same fan and condenser as during recovery and thence is returned to the drum through a chamber in which is the refrigerated surface.

3. A method according to claim 2, in which the refrigerated surface is the exterior of a body of substantial thermal capacity, and the body is refrigerated during recovery as well as during deodorizing.

4. A method according to claim 1, in which during deodorizing the air is passed through the same fan, condenser and heater as during recovery, and the refrigerated surface lies in the circuit between the condenser and the heater and is refrigerated only during deodoriz- 5. A method according to claim 1, in which the solvent used is a composition containing 1,1,1 trichloroethane and a stabiliser.

6. A method according to claim 1, in which the temperature of the refrigerated surface during deodorizing is about 20C. 

2. A method according to claim 1, in which during deodorizing the air is passed through the same fan and condenser as during recovery and thence is returned to the drum through a chamber in which is the refrigerated surface.
 3. A method according to claim 2, in which the refrigerated surface is the exterior of a body of substantial thermal capacity, and the body is refrigerated during recovery as well as during deodorizing.
 4. A method according to claim 1, in which during deodorizing the air is passed through the same fan, condenser and heater as during recovery, and the refrigerated surface lies in the circuit between the condenser and the heater and is refrigerated only during deodorizing.
 5. A method according to claim 1, in which the solvent used is a composition containing 1,1,1 trichloroethane and a stabiliser.
 6. A method according to claim 1, in which the temperature of the refrigerated surface during deodorizing is about -20*C. 